The applicant proposes to examine excitatory and inhibitory receptors in bipolar cells, using whole cell and perforated-patch electrophysiological methods in both the isolated cell and slice preparations of the skate retina. One goal will be to provide a detailed description of the effects of zinc on GABA-A and GABA-C receptors and determine how this influences synaptic transmission between photoreceptors and bipolar cells. The second goal will be to extend studies that will establish that there are ON and OFF bipolars in the skate retina. The types of glutamate receptors on bipolar cells will be examined and compared to immunohistochemical, morphological markers.